JP6798545B2 - Binder composition for non-aqueous secondary battery electrodes, slurry composition for non-aqueous secondary battery electrodes, electrodes for non-aqueous secondary batteries and non-aqueous secondary batteries - Google Patents

Description

The present invention relates to a binder composition for a non-aqueous secondary battery electrode, a slurry composition for a non-aqueous secondary battery electrode, a non-aqueous secondary battery electrode, and a non-aqueous secondary battery.

Non-aqueous secondary batteries such as lithium-ion secondary batteries (hereinafter, may be simply abbreviated as "secondary batteries") are small and lightweight, have high energy density, and can be repeatedly charged and discharged. Yes, it is used for a wide range of purposes. Therefore, in recent years, improvement of battery members such as electrodes has been studied for the purpose of further improving the performance of non-aqueous secondary batteries.

Here, an electrode for a secondary battery such as a lithium ion secondary battery usually includes a current collector and an electrode mixture layer formed on the current collector. Then, the electrode mixture layer is formed by, for example, applying a slurry composition obtained by dispersing an electrode active material and a binder composition containing a binder in a dispersion medium on a current collector and drying the mixture. Will be done.

Conventionally, as a polymer that can be used as a binder for an electrode of a secondary battery, for example, a synthetic resin such as polyvinylidene fluoride, an acrylic polymer and a diene polymer, and a natural resin such as natural rubber (See, for example, Patent Document 1).

International Publication No. 2014/081035

However, in recent years, further improvement in the performance of secondary batteries has been required. Therefore, in the above-mentioned conventional binder composition, a non-aqueous system provided with the electrode while increasing the peel strength of the electrode produced by using the binder composition. There was room for improvement in terms of further improving the battery characteristics (cycle characteristics, etc.) of the secondary battery.

Therefore, the present invention is a binder composition for a non-aqueous secondary battery electrode capable of forming an electrode for a non-aqueous secondary battery which is excellent in peel strength and can exhibit excellent cycle characteristics in a non-aqueous secondary battery. An object of the present invention is to provide a slurry composition for a non-aqueous secondary battery electrode.
Another object of the present invention is to provide an electrode for a non-aqueous secondary battery, which has excellent peel strength and can exhibit excellent cycle characteristics in a non-aqueous secondary battery.
A further object of the present invention is to provide a non-aqueous secondary battery having excellent cycle characteristics.

The present inventor has conducted diligent studies for the purpose of solving the above problems. By using a particulate polymer containing an aliphatic conjugated diene monomer unit and a carboxylic acid group-containing monomer unit in a predetermined ratio, the present inventor has excellent binding property and It has been found that a binder composition for a non-aqueous secondary battery electrode capable of exhibiting excellent cycle characteristics in a non-aqueous secondary battery can be obtained. In addition, the present inventor has a particulate weight containing an aliphatic conjugated diene monomer unit and a (meth) acrylic acid ester monomer unit in a predetermined ratio, respectively, and the degree of swelling of the electrolytic solution is within a predetermined range. By using the coalescence, it is possible to obtain a binder composition for a non-aqueous secondary battery electrode, which has excellent binding properties and can exhibit excellent cycle characteristics and rate characteristics in a non-aqueous secondary battery. I found it. Based on these new discoveries, the inventor has completed the invention.

That is, the first aspect of the present invention is intended to advantageously solve the above problems, and the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention has a particulate weight. A binder composition for a non-aqueous secondary battery electrode containing a coalesced A1, wherein the particulate polymer A1 contains 70% by mass or more and 99% by mass or less of an aliphatic conjugated diene monomer unit, and a carboxylic acid group-containing single amount. It is characterized by containing a body unit in a proportion of 1% by mass or more and 30% by mass or less. As described above, when the binder composition containing the particulate polymer A1 having a predetermined composition is used, an electrode having excellent peel strength and capable of exhibiting excellent cycle characteristics in a non-aqueous secondary battery is formed. be able to.

That is, the second aspect of the present invention is intended to advantageously solve the above problems, and the binder composition for a non-aqueous secondary battery electrode of the second aspect of the present invention is in the form of particles. A binder composition for a non-aqueous secondary battery electrode containing the polymer A2, wherein the particulate polymer A2 contains 70% by mass or more and 95% by mass or less of the aliphatic conjugated diene monomer unit, and (meth) acrylic acid. The ester monomer unit is contained in a proportion of 1% by mass or more and 30% by mass or less, and the electrolytic solution swelling degree of the particulate polymer A2 is 1.2 times or more and 7.0 times or less. .. As described above, by using the binder composition containing the particulate polymer A2 having a predetermined composition and the degree of swelling of the electrolytic solution, it is possible to exhibit excellent peel strength and excellent cycle characteristics in a non-aqueous secondary battery. It is possible to form an electrode that can be formed. In addition, this electrode can also exhibit excellent rate characteristics in a non-aqueous secondary battery.
In the present invention, the "electrolyte swelling degree" can be measured by using the measuring method described in the examples of the present specification.

Here, in the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention, it is preferable that the particulate polymer A1 is a graft copolymer. By using the particulate polymer A1 which is a graft copolymer, it is possible to suppress the generation of aggregates caused by the particulate polymer A1 and enhance the stability of the slurry composition containing the binder composition. Thereby, when the slurry composition is passed through the filter for removing agglomerates and foreign substances, clogging of the filter can be prevented.

Further, in the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention, it is preferable that the volume average particle diameter of the particulate polymer A1 is 0.6 μm or more and 2.5 μm or less. When the volume average particle diameter of the particulate polymer A is 0.6 μm or more and 2.5 μm or less, the cycle characteristics of the non-aqueous secondary battery can be further improved.
In the present invention, the "volume average particle diameter" refers to the particle diameter (D50) at which the cumulative volume calculated from the small diameter side is 50% in the particle diameter distribution (volume basis) measured by the laser diffraction method. .. The "volume average particle size" of various polymers such as the particulate polymer A1 and the particulate polymer A2 can be measured by using the measuring method described in the examples of the present specification.

The binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention further contains a particulate polymer B, and the volume average particle diameter of the particulate polymer B is 0.01 μm or more. It is preferably less than 6 μm. When the particulate polymer B having a volume average particle diameter of 0.01 μm or more and less than 0.6 μm is used in combination with the above-mentioned particulate polymer A1, the peel strength of the electrode produced by using the binder composition can be further improved. At the same time, the cycle characteristics of the non-aqueous secondary battery can be further improved. In addition, by using the particulate polymers A1 and B in combination, the stability of the slurry composition containing the binder composition can be improved.

Here, in the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention, the content of the particulate polymer A1 is the sum of the particulate polymer A1 and the particulate polymer B. The content is preferably 50% by mass or more and 90% by mass or less. When the content of the particulate polymer A1 is within the above range, the peel strength of the electrode can be further improved while suppressing the deterioration of the stability of the slurry composition containing the binder composition.

Further, in the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention, it is preferable that the particulate polymer A2 is a graft copolymer. If the particulate polymer A2, which is a graft copolymer, is used, the rate characteristics of the non-aqueous secondary battery can be further improved. In addition, if the particulate polymer A2, which is a graft copolymer, is used, it is possible to suppress the generation of aggregates caused by the particulate polymer A2 and enhance the stability of the slurry composition containing the binder composition. .. Thereby, when the slurry composition is passed through the filter for removing agglomerates and foreign substances, clogging of the filter can be prevented.

Here, in the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention, it is preferable that the volume average particle diameter of the particulate polymer A2 is 0.6 μm or more and 2.5 μm or less. When the volume average particle diameter of the particulate polymer A2 is 0.6 μm or more and 2.5 μm or less, the cycle characteristics and rate characteristics of the non-aqueous secondary battery can be further improved.

Further, the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention further contains a particulate polymer B, and the volume average particle diameter of the particulate polymer B is 0.01 μm or more. It is preferably less than 6 μm. When the particulate polymer B having a volume average particle diameter of 0.01 μm or more and less than 0.6 μm is used in combination with the above-mentioned particulate polymer A2, the peel strength of the electrode produced by using the binder composition can be further improved. At the same time, the cycle characteristics and rate characteristics of the non-aqueous secondary battery can be further improved. In addition, the combined use of the particulate polymers A2 and B can improve the stability of the slurry composition containing the binder composition.

Then, in the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention, the content of the particulate polymer A2 is the total content of the particulate polymer A2 and the particulate polymer B. It is preferably 50% by mass or more and 90% by mass or less of the amount. When the content of the particulate polymer A2 is within the above range, the peel strength of the electrode can be further improved while suppressing the deterioration of the stability of the slurry composition containing the binder composition.

Further, the present invention aims to advantageously solve the above problems, and the slurry composition for a non-aqueous secondary battery electrode of the present invention comprises an electrode active material and the above-mentioned non-aqueous secondary battery electrode. It is characterized by containing any of the binder compositions for use. As described above, if the slurry composition contains a binder composition containing the particulate polymer A1 or the particulate polymer A2, the peel strength is excellent and the non-aqueous secondary battery exhibits excellent cycle characteristics. It is possible to form an electrode that can be formed. Further, when the binder composition containing the particulate polymer A2 is used, it is possible to make the non-aqueous secondary battery exhibit excellent rate characteristics.

Here, in the slurry composition for a non-aqueous secondary battery electrode of the present invention, the tap density of the electrode active material is preferably 1.1 g / cm ³ or less. When the tap density of the electrode active material is 1.1 g / cm ³ or less, it is possible to form an electrode that is unlikely to swell due to charging / discharging of a non-aqueous secondary battery. Normally, an electrode formed by using an electrode active material having a low tap density tends to have a decrease in peel strength, but if a binder composition containing the particulate polymer A1 or the particulate polymer A2 is used, The peel strength of the electrode can be sufficiently improved.
In the present invention, the "tap density" can be measured by using the measuring method described in the examples of the present specification.

The slurry composition for a non-aqueous secondary battery electrode of the present invention preferably further contains a conductive material. If the slurry composition contains a conductive material, the rate characteristics of the non-aqueous secondary battery can be improved.

The present invention also aims to advantageously solve the above problems, and the electrode for a non-aqueous secondary battery of the present invention is any of the above-mentioned slurry compositions for a non-aqueous secondary battery electrode. It is characterized by including an electrode mixture layer formed in use. As described above, if the electrode mixture layer is formed by using the above-mentioned slurry composition for a non-aqueous secondary battery electrode, the peel strength is excellent and the non-aqueous secondary battery exhibits excellent cycle characteristics. An electrode for a non-aqueous secondary battery can be obtained. Further, when the binder composition containing the particulate polymer A2 is used, it is possible to make the non-aqueous secondary battery exhibit excellent rate characteristics.

An object of the present invention is to solve the above problems advantageously, and the non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, an electrolytic solution and a separator, and at least one of the positive electrode and the negative electrode. Is the electrode for the non-aqueous secondary battery described above. As described above, if the above-mentioned electrode for a non-aqueous secondary battery is used, the battery characteristics such as the cycle characteristics can be sufficiently improved. Further, when the binder composition containing the particulate polymer A2 is used, it is possible to make the non-aqueous secondary battery exhibit excellent rate characteristics.

According to the present invention, a binder composition for a non-aqueous secondary battery electrode capable of forming an electrode for a non-aqueous secondary battery which is excellent in peel strength and can exhibit excellent cycle characteristics in a non-aqueous secondary battery. And a slurry composition for a non-aqueous secondary battery electrode can be provided.
Further, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery which has excellent peel strength and can exhibit excellent cycle characteristics in a non-aqueous secondary battery.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery having excellent battery characteristics such as cycle characteristics.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the binder composition for a non-aqueous secondary battery electrode of the present invention can be used when preparing a slurry composition for a non-aqueous secondary battery electrode. Then, the slurry composition for a non-aqueous secondary battery electrode prepared by using the binder composition for a non-aqueous secondary battery electrode of the present invention is used when forming an electrode of a non-aqueous secondary battery such as a lithium ion secondary battery. Can be used for. Further, the non-aqueous secondary battery of the present invention is characterized by using an electrode for a non-aqueous secondary battery formed by using the slurry composition for the non-aqueous secondary battery electrode of the present invention.
The binder composition for a non-aqueous secondary battery electrode and the slurry composition for a non-aqueous secondary battery electrode of the present invention can be particularly preferably used when forming a negative electrode of a non-aqueous secondary battery.

(Binder composition for non-aqueous secondary battery electrodes)
The binder composition for a non-aqueous secondary battery electrode of the present invention contains a particulate polymer A1 or a particulate polymer A2 (hereinafter, these may be collectively referred to as "particulate polymer A"), and is optional. Further contains the particulate polymer B and other components that can be incorporated into the electrodes of the secondary battery. Further, the binder composition for a non-aqueous secondary battery electrode of the present invention usually further contains a dispersion medium such as water.
Here, in the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention, the particulate polymer A1 contains an aliphatic conjugated diene monomer unit of 70% by mass or more and 99% by mass or less, and a carboxylic acid. Each group-containing monomer unit is contained in a proportion of 1% by mass or more and 30% by mass or less.
When the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention is used for forming an electrode mixture layer of an electrode because the particulate polymer A1 has a predetermined composition. In addition, the electrode active materials and the electrode active materials and the current collector can be satisfactorily bonded to each other. Therefore, if the binder composition for a non-aqueous secondary battery electrode according to the first aspect of the present invention is used, an electrode having excellent peel strength can be obtained, and the binder composition containing the particulate polymer A1 is used. By using the above-mentioned electrodes, excellent battery characteristics, particularly cycle characteristics, can be exhibited in non-aqueous secondary batteries.

Further, in the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention, the particulate polymer A2 contains 70% by mass or more and 95% by mass or less of the aliphatic conjugated diene monomer unit (meth). The acrylic acid ester monomer unit is contained in a proportion of 1% by mass or more and 30% by mass or less, and the swelling degree of the electrolytic solution is 1.2 times or more and 7.0 times or less.
When the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention is used for forming an electrode mixture layer of an electrode because the particulate polymer A2 has a predetermined composition. In addition, the electrode active materials and the electrode active materials and the current collector can be well bound to each other. In addition, since the particulate polymer A2 has a predetermined degree of swelling of the electrolytic solution, lithium is suppressed while suppressing elution of the particulate polymer A2 into the electrolytic solution and cutting of the conductive path by the particulate polymer A2. The mobility of charge carriers such as ions can be ensured, and the resistance of the secondary battery can be suppressed sufficiently low. Therefore, if the binder composition for a non-aqueous secondary battery electrode according to the second aspect of the present invention is used, an electrode having excellent peel strength can be obtained, and the binder composition containing the particulate polymer A2 is used. By using the above-mentioned electrodes, excellent battery characteristics, particularly cycle characteristics and rate characteristics, can be exhibited in a non-aqueous secondary battery.

<Particulate polymer A1>
The particulate polymer A1 is used in an electrode produced by forming an electrode mixture layer on a current collector using a slurry composition for a non-aqueous secondary battery electrode prepared by using a binder composition. The components contained in the material layer are held so as not to be separated from the electrode mixture layer (that is, they function as a binder).

[Composition of Particulate Polymer A1]
The particulate polymer A1 is required to contain an aliphatic conjugated diene monomer unit and a carboxylic acid group-containing monomer unit as repeating units, and optionally, an aliphatic conjugated diene monomer unit and a carboxylic acid. It further contains a monomer unit other than the acid group-containing monomer unit (hereinafter, may be referred to as “other monomer unit”).

[[Aliphatic conjugated diene monomer unit]]
Here, the aliphatic conjugated diene monomer capable of forming the aliphatic conjugated diene monomer unit is not particularly limited, and 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene) is used. , 2,3-Dimethyl-1,3-butadiene and the like. Among them, as the aliphatic conjugated diene monomer, 1,3-butadiene and isoprene are preferable, and isoprene is more preferable. As the aliphatic conjugated diene monomer, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The ratio of the aliphatic conjugated diene monomer unit in the particulate polymer A1 is 70% by mass or more and 99% by mass or less when the amount of all the repeating units in the particulate polymer A1 is 100% by mass. It is necessary that it is 75% by mass or more, more preferably 76% by mass or more, further preferably 82% by mass or more, particularly preferably 90% by mass or more, 98. It is preferably 9% by mass or less, more preferably 97% by mass or less, and further preferably 95% by mass or less. By setting the content ratio of the aliphatic conjugated diene monomer unit to be equal to or higher than the lower limit of the above range, the peel strength of the electrode produced by using the binder composition can be improved, and the content ratio is set to be equal to or lower than the upper limit of the above range. As a result, the cycle characteristics of the secondary battery can be improved.

In addition, the aliphatic conjugated diene monomer can usually form at least cis-1,4 bond, trans-1,4 bond and vinyl bond monomer units by a polymerization reaction. Specifically, for example, 1,3-butadiene can usually form monomeric units of cis-1,4 bond, trans-1,4 bond and 1,2 bond (vinyl bond) by a polymerization reaction. In addition, for example, isoprene is usually a monomer unit of cis-1,4 bond and trans-1,4 bond, and a monomer unit of 1,2 bond and 3,4 bond (vinyl bond) by a polymerization reaction. Can be formed. In the aliphatic conjugated diene monomer unit of the particulate polymer A1, the ratio of cis-1,4 bonds is preferably 50 mol% or more and 100 mol% or less, and 55 mol% or more. It is more preferably 60 mol% or more, further preferably 95 mol% or more, and particularly preferably 99 mol% or more. If the ratio of the monomer unit of cis-1,4 bond in the aliphatic conjugated diene monomer unit (100 mol%) of the particulate polymer A1 is equal to or higher than the lower limit of the above range, a binder composition is used. The peel strength of the electrode thus produced can be further improved, and the cycle characteristics of the secondary battery using the electrode can be further improved. The ratio of the cis-1,4 bond monomer unit to the aliphatic conjugated diene monomer unit can be determined in accordance with the IR method of JIS K6239.

[[Carboxylic acid group-containing monomer unit]]
Here, examples of the carboxylic acid group-containing monomer capable of forming a carboxylic acid group-containing monomer unit include monocarboxylic acid and its derivative, dicarboxylic acid and its acid anhydride, and their derivatives.
Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid.
Examples of the monocarboxylic acid derivative include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, β-diaminoacrylic acid and the like. Can be mentioned.
Examples of the dicarboxylic acid include maleic acid, fumaric acid, and itaconic acid.
Examples of the dicarboxylic acid derivative include methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, methylallyl maleate, diphenyl maleate, nonyl maleate, decyl maleate, and dodecyl maleate. , Octadecil maleate, fluoroalkyl maleate and the like.
Examples of the acid anhydride of the dicarboxylic acid include maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride.
Further, as the carboxylic acid group-containing monomer, an acid anhydride that produces a carboxyl group by hydrolysis can also be used.
In addition, monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, monoethyl fumarate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, monocyclohexyl fumarate, dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate Also included are monoesters and diesters of α, β-ethylene unsaturated polyvalent carboxylic acids such as monobutyl itaconate and dibutyl itaconate. Of these, acrylic acid and methacrylic acid are preferable as the carboxylic acid group-containing monomer. As the carboxylic acid group-containing monomer, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The ratio of the carboxylic acid group-containing monomer unit in the particulate polymer A1 is 1% by mass or more and 30% by mass or less when the amount of all repeating units in the particulate polymer A1 is 100% by mass. It is necessary to be 2% by mass or more, more preferably 3% by mass or more, preferably 26% by mass or less, more preferably 25% by mass or less, and 20% by mass. It is more preferably% or less. By setting the content ratio of the carboxylic acid group-containing monomer unit to the lower limit value of the above range or more, the stability of the slurry composition containing the binder composition can be improved, and the content ratio should be set to the upper limit value or less of the above range. Therefore, the peel strength of the electrode produced by using the binder composition can be increased, and the cycle characteristics of the secondary battery using the electrode can be improved.

[[Other monomeric units]]
The above-mentioned fat is not particularly limited as the monomer unit other than the above-mentioned aliphatic conjugated diene monomer unit and the carboxylic acid group-containing monomer unit that can be contained in the particulate polymer A1. Examples thereof include repeating units derived from known monomers copolymerizable with group-conjugated diene monomers and carboxylic acid group-containing monomers. Specifically, the other monomer unit is not particularly limited, and for example, an aromatic vinyl monomer unit, a (meth) acrylic acid ester monomer unit, and a carboxylic acid group-containing monomer. Examples thereof include a hydrophilic group-containing monomer unit other than the unit. Here, in the present invention, "(meth) acrylic" means acrylic and / or methacrylic.
In addition, these monomers can be used individually by 1 type or in combination of 2 or more types.

Here, examples of the aromatic vinyl monomer capable of forming an aromatic vinyl monomer unit include styrene, styrene sulfonic acid and salts thereof, α-methylstyrene, butoxystyrene, vinylnaphthalene and the like.

The (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit includes methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and t-butyl. Alkyl acrylates such as acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate. Esters; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl Examples thereof include methacrylic acid alkyl esters such as methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate.

In addition, examples of the hydrophilic group-containing monomer capable of forming a hydrophilic group-containing monomer unit include a polymerizable monomer having a hydrophilic group other than a carboxylic acid group. Specifically, examples of the hydrophilic group-containing monomer include a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, and a hydroxyl group-containing monomer.

Examples of the sulfonic acid group-containing monomer include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, ethyl (meth) acrylic acid-2-sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, and 3 − Allyloxy-2-hydroxypropanesulfonic acid and the like.
In addition, in this invention, "(meth) allyl" means allyl and / or metallyl.

Examples of the phosphate group-containing monomer include -2- (meth) acryloyloxyethyl phosphate, methyl-2- (meth) acryloyloxyethyl phosphate, and ethyl phosphate- (meth) acryloyloxyethyl.
In addition, in this invention, "(meth) acryloyl" means acryloyl and / or methacryloyl.

Examples of the hydroxyl group-containing monomer include ethylenically unsaturated alcohols such as (meth) allyl alcohol, 3-butene-1-ol, and 5-hexene-1-ol; -2-hydroxyethyl acrylate and -2-hydroxyacrylate. Ethylinylate such as hydroxypropyl, -2-hydroxyethyl methacrylate, -2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di-2-hydroxypropyl itaconate, etc. alkanol esters of saturated carboxylic acids; general ^{_{formula: CH 2 = CR 1 -COO- (}} C q H 2q O) p -H ( wherein, p is 2-9 integer, q is an integer from 2 to 4, R ¹ represents hydrogen or methyl group) and esters of polyalkylene glycol and (meth) acrylic acid; 2-hydroxyethyl-2'-(meth) acryloyloxyphthalate, 2-hydroxyethyl-2'- Mono (meth) acrylic acid esters of dihydroxyesters of dicarboxylic acids such as (meth) acryloyloxysuccinate; vinyl ethers such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; (meth) allyl-2-hydroxyethyl ether , (Meta) allyl-2-hydroxypropyl ether, (meth) allyl-3-hydroxypropyl ether, (meth) allyl-2-hydroxybutyl ether, (meth) allyl-3-hydroxybutyl ether, (meth) allyl-4- Mono (meth) allyl ethers of alkylene glycols such as hydroxybutyl ether and (meth) allyl-6-hydroxyhexyl ether; polyoxyalkylene glycol mono such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether. (Meta) allyl ethers; (poly) such as glycerin mono (meth) allyl ether, (meth) allyl-2-chloro-3-hydroxypropyl ether, (meth) allyl-2-hydroxy-3-chloropropyl ether, etc. Mono (meth) allyl ethers of halogens and hydroxy-substituted alkylene glycols; mono (meth) allyl ethers of polyvalent phenols such as eugenol and isoeugenol and halogen-substituted products thereof; (meth) allyl-2-hydroxyethylthioethers, ( Meta) alkylene glycols such as allyl-2-hydroxypropylthioether (Meta) allyl thioethers; etc.

The content ratio of the other monomer units of the particulate polymer A1 is preferably 0% by mass or more and less than 10% by mass, more preferably 8% by mass or less, and further preferably 5% by mass or less. When the content ratio of the other monomer units is less than 10% by mass, it is possible to suppress the deterioration of the stability of the slurry composition containing the binder composition.

[[Characteristics of Particulate Polymer A1]]
The structure of the particulate polymer A1 according to the first aspect of the present invention is not particularly limited and may be any of a block copolymer, a graft copolymer, a random copolymer and the like, but it serves as a trunk portion. A graft copolymer having a structure in which a polymer serving as a graft portion is bonded to the polymer is preferable. If the particulate polymer A1 is a graft copolymer, it is presumed that the graft portion physically suppresses surface contact between the particulate polymers A1 and between the particulate polymer A1 and other components. , It is possible to suppress the generation of aggregates between the particulate polymers A1 and the particulate polymer A1 and other components, and it is possible to improve the stability of the slurry composition containing the binder composition.
When the particulate polymer A1 is a graft copolymer, the graft portion of the particulate polymer A1 preferably contains a carboxylic acid group-containing monomer unit, and the graft portion is a carboxylic acid group-containing monomer. It is more preferable that it consists of only units. When the carboxylic acid group-containing monomer unit is contained in the graft portion, an electric double layer is formed on the surface layer portion of the particulate polymer A1, and the generation of agglomerates can be further suppressed.
When the particulate polymer A1 is a graft copolymer, the proportion of the graft portion in the particulate polymer A1 is the amount of all repeating units in the particulate polymer A1 (the total amount of the trunk portion and the graft portion). ) Is 100% by mass, it is preferably 1% by mass or more, more preferably 2% by mass or more, preferably 30% by mass or less, and more preferably 25% by mass or less. It is preferably 20% by mass or less, and more preferably 20% by mass or less. By setting the content ratio of the graft portion within the above range, it is possible to further improve the peel strength of the electrode and the cycle characteristics of the secondary battery while improving the stability of the slurry composition containing the binder composition.

The volume average particle diameter of the particulate polymer A1 is preferably 0.6 μm or more, more preferably 0.7 μm or more, further preferably 0.8 μm or more, and 2.5 μm or less. It is more preferably 2.0 μm or less, and even more preferably 1.5 μm or less. When the volume average particle diameter of the particulate polymer A1 is not less than the lower limit of the above range, the peel strength of the electrode produced by using the binder composition can be further improved, and when it is not more than the upper limit of the above range. , The peel strength of the electrode produced by using the binder composition can be further improved, and the cycle characteristics of the secondary battery provided with the electrode can be further improved.
The volume average particle size of the particulate polymer A1 can be adjusted as appropriate. For example, when the particulate polymer A1 is the above-mentioned graft copolymer, the volume average particle diameter of the particulate polymer A1 is slightly affected by the graft portion, but is usually the volume average of the polymer serving as the trunk portion. It depends largely on the particle size. Therefore, when natural rubber is used as the polymer to be the trunk portion, the volume average particle size of the particulate polymer A1 is adjusted by adjusting the volume average particle size of the natural rubber by using sedimentation separation or classification. can do. When a polymer obtained by artificially polymerizing is used as the polymer to be the trunk portion, the volume average particle size of the polymer is adjusted according to the polymerization conditions such as the amount of the emulsifier used to form particles. The volume average particle size of the polymer A1 can be adjusted.

[[Method for preparing particulate polymer A1]]
The method for preparing the particulate polymer A1 is not particularly limited, and a known method can be used. For example, the particulate polymer A1 which is a random copolymer can be obtained by polymerizing a monomer composition containing the above-mentioned monomer by a known method, and the particles which are graft copolymers. The state polymer A1 can be obtained by grafting a polymer to be a graft portion to a polymer to be a trunk portion by a known method.
When the particulate polymer A1 which is a graft copolymer is prepared, the method of grafting the graft portion to the polymer which becomes the trunk portion is not particularly limited, and the above-mentioned monomer is placed on the polymer which becomes the trunk portion. Examples thereof include a method of polymerizing a monomer composition containing the above-mentioned monomer and a method of binding a macromer obtained by polymerizing the above-mentioned monomer composition containing a monomer to a polymer serving as a trunk portion. The polymer that becomes the trunk portion of the particulate polymer A1 that is a graft copolymer may be a polymer prepared by artificially polymerizing a monomer composition containing the above-mentioned monomer. It may be natural rubber. Above all, from the viewpoint of further improving the peel strength of the electrode and the cycle characteristics of the secondary battery, it is preferable that the polymer serving as the trunk portion is made of natural rubber. That is, the particulate polymer A1 is preferably a graft copolymer prepared by graft polymerization on natural rubber.

In the present invention, the fact that the graft copolymer was obtained by the above-mentioned method is that the volume average particle size of the polymer serving as the trunk portion before grafting the graft portion (before graft polymerization) and the obtained graft copolymer weight. It can be confirmed by comparing with the volume average particle size of the coalescence. More specifically, if the volume average particle size ratio Δd obtained by the following formula is 1.01 or more, it can be considered that the graft portion is grafted by graft polymerization.
Δd = volume average particle diameter d1 of the graft copolymer d1 / volume average particle diameter d0 of the polymer to be the trunk portion

When the particulate polymer A1 or the polymer to be the trunk portion thereof is prepared by artificially polymerizing the monomer composition, the ratio of each monomer in the monomer composition is determined. Usually, it is the same as the ratio of each monomer unit in the desired polymer. The polymerization mode of these polymers is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a massive polymerization method, or an emulsion polymerization method may be used. Further, as the polymerization reaction, addition polymerization such as ionic polymerization, radical polymerization and living radical polymerization can be used. As the emulsifier, dispersant, polymerization initiator, polymerization aid and the like used for the polymerization, those generally used can be used, and the amount used can also be the amount generally used.

<Particulate polymer A2>
The particulate polymer A2, like the particulate polymer A1, is formed by forming an electrode mixture layer on the current collector using a slurry composition for a non-aqueous secondary battery electrode prepared by using a binder composition. In the manufactured electrode, the components contained in the electrode mixture layer are held so as not to be separated from the electrode mixture layer (that is, they function as a binder).

[Composition of Particulate Polymer A2]
The particulate polymer A2 is required to contain an aliphatic conjugated diene monomer unit and a (meth) acrylic acid ester monomer unit as repeating units, and optionally, an aliphatic conjugated diene monomer unit. And, a monomer unit other than the (meth) acrylic acid ester monomer unit (hereinafter, may be referred to as “other monomer unit”) is further contained.

[[Aliphatic conjugated diene monomer unit]]
Here, the aliphatic conjugated diene monomer capable of forming the aliphatic conjugated diene monomer unit is not particularly limited, and the aliphatic conjugated diene monomer unit of the above-mentioned particulate polymer A1 is formed. Examples include those similar to the possible aliphatic conjugated diene monomers. Of these, 1,3-butadiene and isoprene are preferable as the aliphatic conjugated diene monomer. As the aliphatic conjugated diene monomer, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The ratio of the aliphatic conjugated diene monomer unit in the particulate polymer A2 is 70% by mass or more and 95% by mass or less when the amount of all the repeating units in the particulate polymer A2 is 100% by mass. It is necessary that it is 75% by mass or more, more preferably 76% by mass or more, preferably 90% by mass or less, and more preferably 85% by mass or less. By setting the content ratio of the aliphatic conjugated diene monomer unit to be equal to or higher than the lower limit of the above range, the peel strength of the electrode produced by using the binder composition can be improved, and the content ratio is set to be equal to or lower than the upper limit of the above range. As a result, the cycle characteristics of the secondary battery can be improved.

In addition, the aliphatic conjugated diene monomer can usually form at least cis-1,4 bond, trans-1,4 bond and vinyl bond monomer units by a polymerization reaction. Specifically, for example, 1,3-butadiene can usually form monomeric units of cis-1,4 bond, trans-1,4 bond and 1,2 bond (vinyl bond) by a polymerization reaction. In addition, for example, isoprene is usually a monomer unit of cis-1,4 bond and trans-1,4 bond, and a monomer unit of 1,2 bond and 3,4 bond (vinyl bond) by a polymerization reaction. Can be formed. In the aliphatic conjugated diene monomer unit of the particulate polymer A2, the ratio of cis-1,4 bonds is preferably 50 mol% or more and 100 mol% or less, and 55 mol% or more. It is more preferably 60 mol% or more, further preferably 95 mol% or more, and particularly preferably 99 mol% or more. If the ratio of the cis-1,4 bond monomer unit in the aliphatic conjugated diene monomer unit (100 mol%) of the particulate polymer A2 is equal to or higher than the lower limit of the above range, a binder composition is used. The peel strength of the electrode thus produced can be further improved, and the cycle characteristics and rate characteristics of the secondary battery using the electrode can be further improved.

[[(Meta) acrylic acid ester monomer unit]]
Here, as the (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit, the (meth) acrylic acid ester monomer unit of the above-mentioned particulate polymer A1 is formed. Examples thereof include the same as the obtained (meth) acrylic acid ester monomer. Among them, as the (meth) acrylic acid ester monomer, methyl methacrylate and ethyl acrylate are preferable. As the (meth) acrylic acid ester monomer, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The ratio of the (meth) acrylic acid ester monomer unit in the particulate polymer A2 is 1% by mass or more and 30% by mass when the amount of all repeating units in the particulate polymer A2 is 100% by mass. % Or less, preferably 5% by mass or more, more preferably 8% by mass or more, further preferably 10% by mass or more, and preferably 26% by mass or less. It is more preferably 25% by mass or less. By setting the content ratio of the (meth) acrylic acid ester monomer unit to the lower limit of the above range or more, the rate characteristics of the secondary battery can be improved, and by setting it to the upper limit of the above range or less, the second The cycle characteristics of the next battery can be improved.

[[Other monomeric units]]
The monomer units other than the above-mentioned aliphatic conjugated diene monomer unit and the (meth) acrylic acid ester monomer unit, which can be contained in the particulate polymer A2, are not particularly limited as described above. Examples thereof include repeating units derived from known monomers copolymerizable with the aliphatic conjugated diene monomer and the (meth) acrylic acid ester monomer. Specifically, the other monomer unit is not particularly limited, and examples thereof include an aromatic vinyl monomer unit and a hydrophilic group-containing monomer unit.
In addition, these monomers can be used individually by 1 type or in combination of 2 or more types.

Here, the aromatic vinyl monomer capable of forming the aromatic vinyl monomer unit is the same as the aromatic vinyl monomer capable of forming the aromatic vinyl monomer unit of the particulate polymer A1 described above. Can be mentioned.

Further, examples of the hydrophilic group-containing monomer capable of forming a hydrophilic group-containing monomer unit include a polymerizable monomer having a hydrophilic group. Specifically, examples of the hydrophilic group-containing monomer include a carboxylic acid group-containing monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, and a hydroxyl group-containing monomer.

The carboxylic acid group-containing monomer, sulfonic acid group-containing monomer, phosphoric acid group-containing monomer, and hydroxyl group-containing monomer each contain a carboxylic acid group in the above-mentioned particulate polymer A1. Carboxylic acid group-containing monomer capable of forming a monomer unit, sulfonic acid group-containing monomer capable of forming a sulfonic acid group-containing monomer unit, and phosphoric acid capable of forming a phosphoric acid group-containing monomer unit Examples thereof include a group-containing monomer and the same as the hydroxyl group-containing monomer capable of forming a hydroxyl group-containing monomer unit.

The content ratio of the other monomer units of the particulate polymer A2 is preferably 0% by mass or more and less than 15% by mass when the amount of all repeating units in the particulate polymer A2 is 100% by mass. , More preferably 10% by mass or less, still more preferably 8% by mass or less. When the content ratio of the other monomer units is less than 15% by mass, it is possible to suppress the deterioration of the stability of the slurry composition containing the binder composition.

[[Characteristics of Particulate Polymer A2]]
The structure of the particulate polymer A2 according to the second aspect of the present invention is not particularly limited and may be any of a block copolymer, a graft copolymer, a random copolymer and the like, but it serves as a trunk portion. A graft copolymer having a structure in which a polymer serving as a graft portion is bonded to the polymer is preferable. If the particulate polymer A2 is a graft copolymer, it is presumed that the graft portion physically suppresses surface contact between the particulate polymers A2 and between the particulate polymer A2 and other components. , It is possible to suppress the generation of agglomerates between the particulate polymers A2 and the particulate polymer A2 and other components, and it is possible to improve the stability of the slurry composition containing the binder composition.
When the particulate polymer A2 is a graft copolymer, the graft portion of the particulate polymer A2 preferably contains a (meth) acrylic acid ester monomer unit, and the graft portion is a (meth) acrylic acid. More preferably, it consists of only ester monomer units. By containing the (meth) acrylic acid ester monomer unit in the graft portion, the glass transition temperature of the surface layer portion of the particulate polymer A2 is increased, the generation of aggregates can be further suppressed, and the surface layer portion of the particulate polymer A2 The degree of swelling of the electrolytic solution is increased, and the charge carrier such as lithium ion is moved more smoothly. Therefore, the stability of the slurry composition containing the binder composition can be further improved, and the rate characteristics of the secondary battery can be further improved.
When the particulate polymer A2 is a graft copolymer, the proportion of the graft portion in the particulate polymer A2 is the amount of all repeating units in the particulate polymer A2 (the total amount of the trunk portion and the graft portion). ) Is 100% by mass, it is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and 30% by mass or less. It is preferably 28% by mass or less, and more preferably 28% by mass or less. By setting the content ratio of the graft portion within the above range, the stability of the slurry composition containing the binder composition is improved, and the peel strength of the electrode and the rate characteristics and cycle characteristics of the secondary battery are improved in a well-balanced manner. Can be done.

The volume average particle diameter of the particulate polymer A2 is preferably 0.6 μm or more, more preferably 0.7 μm or more, further preferably 0.8 μm or more, and 2.5 μm or less. It is more preferably 2.0 μm or less, and even more preferably 1.5 μm or less. When the volume average particle diameter of the particulate polymer A2 is not less than the lower limit of the above range, the peel strength of the electrode produced by using the binder composition can be further improved, and when it is not more than the upper limit of the above range. , The peel strength of the electrode produced by using the binder composition can be further improved, and the cycle characteristics and rate characteristics of the secondary battery provided with the electrode can be further improved.
The volume average particle size of the particulate polymer A2 can be adjusted as appropriate. For example, when the particulate polymer A2 is the above-mentioned graft copolymer, the volume average particle diameter of the particulate polymer A2 is slightly affected by the graft portion, but is usually the volume average of the polymer serving as the trunk portion. It depends largely on the particle size. Therefore, when natural rubber is used as the polymer to be the trunk portion, the volume average particle size of the particulate polymer A2 is adjusted by adjusting the volume average particle size of the natural rubber by using sedimentation separation or classification. can do. When a polymer obtained by artificially polymerizing is used as the polymer to be the trunk portion, the volume average particle size of the polymer is adjusted according to the polymerization conditions such as the amount of the emulsifier used to form particles. The volume average particle size of the polymer A2 can be adjusted.

The degree of swelling of the electrolytic solution of the particulate polymer A2 needs to be 1.2 times or more and 7.0 times or less, preferably 2.0 times or more, and 3.5 times or more. More preferably, it is 6.8 times or less, and more preferably 6.5 times or less. When the degree of swelling of the electrolytic solution of the particulate polymer A2 is at least the lower limit of the above range, the rate characteristics of the secondary battery can be further improved. On the other hand, when the degree of swelling of the electrolytic solution of the particulate polymer A is equal to or less than the upper limit of the above range, the elution of the particulate polymer A2 into the electrolytic solution is suppressed, thereby ensuring the cycle characteristics of the secondary battery. In addition, the rate characteristics of the secondary battery can be ensured without cutting the conductive path formed by the electrode active material and / or the conductive material due to excessive swelling of the particulate polymer A2.
The degree of swelling of the electrolytic solution of the particulate polymer A2 can be adjusted by changing the composition of the particulate polymer A2. For example, by increasing the content ratio of the (meth) acrylic acid ester monomer unit, the degree of swelling of the electrolytic solution of the particulate polymer A2 can be increased.

[[Method for preparing particulate polymer A2]]
The method for preparing the particulate polymer A2 is not particularly limited, and a known method can be used. For example, the particulate polymer A2, which is a random copolymer, can be obtained by polymerizing a monomer composition containing the above-mentioned monomer by a known method, and particles which are graft copolymers. The state polymer A2 can be obtained by grafting a polymer to be a graft portion to a polymer to be a trunk portion by a known method.
When the particulate polymer A2, which is a graft copolymer, is prepared, the method of grafting the graft portion to the polymer to be the trunk portion is not particularly limited, and the above-mentioned monomer is placed on the polymer to be the trunk portion. Examples thereof include a method of polymerizing a monomer composition containing the above-mentioned monomer and a method of binding a macromer obtained by polymerizing the above-mentioned monomer composition containing a monomer to a polymer serving as a trunk portion. The polymer that becomes the trunk portion of the particulate polymer A2, which is a graft copolymer, may be a polymer prepared by artificially polymerizing a monomer composition containing the above-mentioned monomer. It may be natural rubber. Above all, from the viewpoint of further improving the peel strength of the electrode and the cycle characteristics and rate characteristics of the secondary battery, it is preferable that the polymer serving as the trunk portion is made of natural rubber. That is, the particulate polymer A2 is preferably a graft copolymer prepared by graft polymerization on natural rubber.

When the particulate polymer A2 or a polymer serving as a trunk portion thereof is prepared by artificially polymerizing the monomer composition, the ratio of each monomer in the monomer composition is , Usually the same as the ratio of each monomer unit in the desired polymer. The polymerization mode of these polymers is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a massive polymerization method, or an emulsion polymerization method may be used. Further, as the polymerization reaction, addition polymerization such as ionic polymerization, radical polymerization and living radical polymerization can be used. As the emulsifier, dispersant, polymerization initiator, polymerization aid and the like used for the polymerization, those generally used can be used, and the amount used can also be the amount generally used.

<Particulate polymer B>
The particulate polymer B is used in an electrode produced by forming an electrode mixture layer on a current collector using a slurry composition for a non-aqueous secondary battery electrode prepared by using a binder composition. The components contained in the material layer are held so as not to be detached from the electrode mixture layer (that is, they function as a binder together with the above-mentioned particulate polymer A1 or particulate polymer A2).

[Composition of Particulate Polymer B]
The composition of the particulate polymer B is not particularly limited, but the particulate polymer B preferably contains an aliphatic conjugated diene monomer unit as a repeating unit. As described above, the particulate polymer B containing the aliphatic conjugated diene monomer unit is optionally other than the aromatic vinyl monomer unit, the aliphatic conjugated diene monomer unit and the aromatic vinyl monomer unit. Further contains at least one of the above-mentioned monomer units (hereinafter, may be referred to as “arbitrary monomer units”). The particulate polymer B preferably contains an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit.

[[Aliphatic conjugated diene monomer unit]]
Here, as the aliphatic conjugated diene monomer capable of forming the aliphatic conjugated diene monomer unit of the particulate polymer B, the aliphatic conjugated diene monomer unit of the particulate polymer A described above is formed. Examples thereof include the same as the aliphatic conjugated diene monomer obtained. Among them, 1,3-butadiene and isoprene are preferable, and 1,3-butadiene is more preferable as the aliphatic conjugated diene monomer forming the aliphatic conjugated diene monomer unit of the particulate polymer B. As the aliphatic conjugated diene monomer, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The ratio of the aliphatic conjugated diene monomer unit in the particulate polymer B is 20% by mass or more when the amount of all the repeating units in the particulate polymer B is 100% by mass. It is preferably 25% by mass or more, more preferably 30% by mass or more, preferably 60% by mass or less, more preferably 55% by mass or less, and 50% by mass or less. It is more preferable to have. When the content ratio of the aliphatic conjugated diene monomer unit is set to be equal to or higher than the lower limit of the above range, the peel strength of the electrode prepared by using the binder composition can be further improved, and is set to be equal to or lower than the upper limit of the above range. This makes it possible to further improve the cycle characteristics of the secondary battery provided with the electrodes produced by using the binder composition.

[[Aromatic vinyl monomer unit]]
Here, as the aromatic vinyl monomer capable of forming the aromatic vinyl monomer unit of the particulate polymer B, the aromatic vinyl capable of forming the other monomer unit of the particulate polymer A1 described above The same as the monomer can be mentioned. Among them, styrene and styrene sulfonate are preferable, and styrene is more preferable, as the aromatic vinyl monomer forming the aromatic vinyl monomer unit of the particulate polymer B. As the aromatic vinyl monomer, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

The ratio of the aromatic vinyl monomer unit in the particulate polymer B is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. It is preferably 70% by mass or less, more preferably 68% by mass or less, and further preferably 65% by mass or less. When the content ratio of the aromatic vinyl monomer unit is set to be equal to or higher than the lower limit of the above range, the cycle characteristics of the secondary battery provided with the electrode produced by using the binder composition can be further improved, and the upper limit of the above range can be further improved. When it is less than the value, the peel strength of the electrode produced by using the binder composition can be further improved.

[[Any monomer unit]]
Any monomer unit other than the above-mentioned aliphatic conjugated diene monomer unit and aromatic vinyl monomer unit that can be contained in the particulate polymer B is not particularly limited, and the above-mentioned aliphatic monomer unit is not particularly limited. Repeat units derived from known monomers copolymerizable with conjugated diene monomers and aromatic vinyl monomers. Specifically, the arbitrary monomer unit is not particularly limited, and examples thereof include a hydrophilic group-containing monomer unit and a (meth) acrylic acid ester monomer unit.
In addition, these monomers can be used individually by 1 type or in combination of 2 or more types.

Here, as the hydrophilic group-containing monomer and the (meth) acrylic acid ester monomer capable of forming the hydrophilic group-containing monomer unit and the (meth) acrylic acid ester monomer unit of the particulate polymer B. Is hydrophilic other than the carboxylic acid group-containing monomer capable of forming the carboxylic acid group-containing monomer unit of the particulate polymer A1 and the carboxylic acid group-containing monomer capable of forming other monomer units. Examples thereof include a sex group-containing monomer and the same as the (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit of the particulate polymer A1 described above. Among them, the carboxylic acid group-containing monomer and the hydroxyl group-containing monomer are preferable as the hydrophilic group-containing monomer forming the hydrophilic group-containing monomer unit of the particulate polymer B. The carboxylic acid group-containing monomer is preferably itaconic acid, and the hydroxyl group-containing monomer is preferably 2-hydroxyethyl acrylate (-2-hydroxyethyl acrylate). As the (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit, methyl methacrylate and 2-ethylhexyl acrylate are preferable.

The content ratio of any monomer unit of the particulate polymer B is preferably 0% by mass or more and 10% by mass or less, more preferably 7% by mass or less, and further preferably 5% by mass or less.

[Volume average particle size]
The volume average particle size of the particulate polymer B needs to be 0.01 μm or more and less than 0.6 μm, preferably 0.05 μm or more, more preferably 0.1 μm or more, and 0. It is preferably 5.5 μm or less, more preferably 0.4 μm or less, and even more preferably 0.3 μm or less. When the volume average particle diameter of the particulate polymer B is 0.01 μm or more, it is possible to suppress the deterioration of the stability of the slurry composition containing the binder composition. Further, when the volume average particle diameter of the particulate polymer B is less than 0.6 μm, the peel strength of the electrode produced by using the binder composition can be sufficiently improved, and the secondary battery provided with the electrode can be sufficiently improved. The cycle characteristics and rate characteristics of the above can be sufficiently improved.
The volume average particle size of the particulate polymer B can be adjusted by changing the polymerization conditions such as the amount of the emulsifier used.

[Method for preparing particulate polymer B]
The particulate polymer B having the above-mentioned composition is not particularly limited, and can be prepared by polymerizing the above-mentioned monomer-containing monomer composition. Here, the ratio of each monomer in the monomer composition is usually the same as the ratio of each monomer unit in the desired polymer. The polymerization mode of the particulate polymer B is not particularly limited, and any method such as a solution polymerization method, a suspension polymerization method, a massive polymerization method, or an emulsion polymerization method may be used. Further, as the polymerization reaction, addition polymerization such as ionic polymerization, radical polymerization and living radical polymerization can be used. As the emulsifier, dispersant, polymerization initiator, polymerization aid and the like used for the polymerization, those generally used can be used, and the amount used can also be the amount generally used.

<Content ratio of particulate polymer>
The content of the particulate polymer A (particle-like polymer A1 or particle-like polymer A2) in the binder composition for the non-aqueous secondary battery electrode of the present invention is the particle-like polymer A and the particle-like polymer. The total content with B is preferably 50% by mass or more, more preferably 55% by mass or more, preferably 90% by mass or less, more preferably 85% by mass or less, and 80% by mass. It is more preferably mass% or less. When the ratio of the content of the particulate polymer A to the total content of the particulate polymer A and the particulate polymer B is equal to or higher than the lower limit of the above range, the peel strength of the electrode produced by using the binder composition Can be further improved. Further, when the ratio of the content of the particulate polymer A is not more than the upper limit of the above range, it is possible to suppress the deterioration of the stability of the slurry composition containing the binder composition.
The binder composition for a non-aqueous secondary battery electrode of the present invention may contain any polymer other than the above-mentioned particulate polymer A and particulate polymer B as a binder.

<Dispersion medium>
The dispersion medium contained in the binder composition for a non-aqueous secondary battery electrode of the present invention is not particularly limited, and examples thereof include water. The dispersion medium may be an aqueous solution of an arbitrary compound or a mixed solution of a small amount of an organic solvent and water.

<Other ingredients>
In addition to the above components, the binder composition for a non-aqueous secondary battery electrode of the present invention may contain components such as a reinforcing material, a leveling agent, a viscosity modifier, and an electrolyte solution additive. These are not particularly limited as long as they do not affect the battery reaction, and known ones, for example, those described in International Publication No. 2012/115096 can be used. In addition, one of these components may be used alone, or two or more of these components may be used in combination at any ratio.

<Preparation method of binder composition>
The binder composition for a non-aqueous secondary battery electrode of the present invention is not particularly limited, and for example, a dispersion liquid containing the particulate polymer A obtained by polymerization may be used as it is as the binder composition. Then, the dispersion liquid containing the particulate polymer B as an optional component and the other components described above may be added and mixed with the dispersion liquid containing the particulate polymer A to obtain a binder composition. When the binder composition is prepared using the dispersion liquid of the particulate polymer, the liquid component contained in the dispersion liquid may be used as it is as the dispersion medium of the binder composition.

(Slurry composition for non-aqueous secondary battery electrodes)
The slurry composition for a non-aqueous secondary battery electrode of the present invention contains an electrode active material and the above-mentioned binder composition, and optionally further contains other components. That is, the slurry composition for a non-aqueous secondary battery electrode of the present invention usually contains an electrode active material, the above-mentioned particulate polymer A1 or particulate polymer A2, and a dispersion medium, and optionally contains particles. It further contains a state polymer B, a conductive material and other components. Since the slurry composition for a non-aqueous secondary battery electrode of the present invention contains the above-mentioned binder composition, when used for forming the electrode mixture layer of the electrode, the electrode active materials and the electrode active material are used. And the current collector can be well bound. Therefore, if the slurry composition for a non-aqueous secondary battery electrode of the present invention is used, an electrode having excellent peel strength can be obtained. Further, if an electrode formed by using the slurry composition containing the binder composition is used, excellent battery characteristics, particularly cycle characteristics, can be exhibited in the non-aqueous secondary battery. Further, when the binder composition containing the particulate polymer A2 is used, it is possible to make the non-aqueous secondary battery exhibit excellent rate characteristics.
In the following, a case where the slurry composition for a non-aqueous secondary battery electrode is a slurry composition for a lithium ion secondary battery negative electrode will be described as an example, but the present invention is not limited to the following example.

<Electrode active material>
The electrode active material is a substance that transfers electrons at the electrodes of a secondary battery. Then, as the negative electrode active material for the lithium ion secondary battery, a substance capable of storing and releasing lithium is usually used.

Specifically, examples of the negative electrode active material for a lithium ion secondary battery include a carbon-based negative electrode active material, a metal-based negative electrode active material, and a negative electrode active material combining these.

Here, the carbon-based negative electrode active material refers to an active material having carbon as a main skeleton into which lithium can be inserted (also referred to as “dope”), and examples of the carbon-based negative electrode active material include carbonaceous materials and graphite. Quality material is mentioned.

Examples of the carbonaceous material include easy-to-graphite carbon and non-graphitable carbon having a structure close to an amorphous structure typified by glassy carbon.
Here, as the easy-to-graphite carbon, for example, a carbon material made from tar pitch obtained from petroleum or coal can be mentioned. Specific examples include coke, mesocarbon microbeads (MCMB), mesophase pitch carbon fibers, and pyrolysis vapor phase grown carbon fibers.
Examples of non-graphitizable carbon include calcined phenolic resin, polyacrylonitrile-based carbon fiber, pseudoisotropic carbon, calcined furfuryl alcohol resin (PFA), and hard carbon.

Further, as the graphitic material, for example, natural graphite, artificial graphite and the like can be mentioned.
Here, as the artificial graphite, for example, artificial graphite obtained by heat-treating carbon containing easily graphitable carbon mainly at 2800 ° C. or higher, graphitized MCMB obtained by heat-treating MCMB at 2000 ° C. or higher, and mesophase pitch-based carbon fiber at 2000 ° C. Examples thereof include graphitized mesophase-pitch carbon fibers heat-treated as described above.

Further, the metal-based negative electrode active material is an active material containing a metal, and usually contains an element into which lithium can be inserted in the structure, and the theoretical electric capacity per unit mass when lithium is inserted is 500 mAh /. An active material having a mass of g or more. Examples of the metal-based active material include lithium metal and elemental metals capable of forming a lithium alloy (for example, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn. , Sr, Zn, Ti, etc.) and their alloys, and their oxides, sulfides, nitrides, silides, carbides, phosphors, etc. are used. Among these, as the metal-based negative electrode active material, an active material containing silicon (silicon-based negative electrode active material) is preferable. This is because the capacity of the lithium ion secondary battery can be increased by using the silicon-based negative electrode active material.

Examples of the silicon-based negative electrode active material include silicon (Si), an alloy containing silicon, SiO, SiO _x , and a composite of a Si-containing material obtained by coating or compounding a Si-containing material with conductive carbon and conductive carbon. And so on. As these silicon-based negative electrode active materials, one type may be used alone, or two types may be used in combination.

[Properties of electrode active material]
The tap density of the electrode active material is preferably 1.1 g / cm ³ or less, more preferably 1.05 g / cm ³ or less, and further preferably 1.03 g / cm ³ or less. .. The electrode active material expands and contracts with charge and discharge, but if the tap density of the electrode active material is set to the above upper limit value or less, it is possible to form an electrode in which swelling due to charge and discharge is unlikely to occur. Incidentally, the tap density of the electrode active material is usually at 0.7 g / cm ³ or more, preferably 0.75 g / cm ³ or more, and more preferably 0.8 g / cm ³ or more.

Here, the electrode active material having a low tap density generally has fine irregularities. Therefore, when only a particulate polymer having a small particle size is used as the binder, the particulate polymer gets into the recesses of the electrode active material having a low tap density, and the electrode active material is bound well. It may not be possible to make it. On the other hand, when only a particulate polymer having a large particle size is used as the binder, the contact area between the electrode active material and the particulate polymer is reduced, and the electrode active material is bound well. It may not be possible. Therefore, in the slurry composition for a non-aqueous secondary battery electrode of the present invention, if a particulate polymer B having a relatively small volume average particle diameter is used in addition to the particulate polymer A, an electrode active material having a low tap density is used. Even when the above is used, it is possible to form an electrode having sufficiently excellent peel strength.

<Binder composition>
As the binder composition, a binder composition for a non-aqueous secondary battery electrode containing the above-mentioned particulate polymer A1 or particulate polymer A2 can be used.
The blending amount of the binder composition is not particularly limited, and for example, the amount of the particulate polymer A per 100 parts by mass of the electrode active material in terms of solid content (the binder composition further comprises the particulate polymer B). When it is contained, the amount (total amount of the particulate polymer A and the particulate polymer B) can be 0.5 parts by mass or more and 4.0 parts by mass or less.

<Conductive material>
The conductive material is for ensuring electrical contact between the electrode active materials in the electrode mixture layer. The conductive material used in the slurry composition of the present invention is not particularly limited, and a known conductive material can be used. Specifically, the conductive material includes acetylene black, Ketjen black (registered trademark), furnace black, graphite, carbon fiber, carbon flakes, carbon ultrashort fibers (for example, carbon nanotubes and vapor-grown carbon fibers), etc. Conductive carbon material; various metal fibers, foils and the like can be used. Among these, from the viewpoint of sufficiently improving the rate characteristics while maintaining the battery capacity of the secondary battery, it is preferable to use acetylene black, ketjen black, or furnace black as the conductive material.
The blending amount of the conductive material is not particularly limited, and is, for example, 0.1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the electrode active material.

<Other ingredients>
Other components that can be blended in the slurry composition include, without particular limitation, the same components as those that can be blended in the binder composition of the present invention. As for other components, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio.

<Preparation of slurry composition>
The above-mentioned slurry composition can be prepared by dispersing or dissolving each of the above-mentioned components in a dispersion medium such as water. Specifically, the above components and the dispersion medium are mixed using a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, a grinder, an ultrasonic disperser, a homogenizer, a planetary mixer, and a fill mix. Allows the slurry composition to be prepared. The mixing of each of the above components with the dispersion medium can usually be carried out in the range of room temperature to 80 ° C. for 10 minutes to several hours. Further, as the dispersion medium used for preparing the slurry composition, the same dispersion medium as the binder composition can be used. The dispersion medium used for preparing the slurry composition may also include the dispersion medium contained in the binder composition.

(Electrodes for non-aqueous secondary batteries)
The electrode for a non-aqueous secondary battery of the present invention includes an electrode mixture layer formed by using the above-mentioned slurry composition for a non-aqueous secondary battery electrode, and is usually a current collector and a current collector. It has an electrode mixture layer formed on the top. The electrode mixture layer contains at least an electrode active material and a polymer derived from the particulate polymer A1 or the particulate polymer A2. Each component contained in the electrode mixture layer was contained in the above-mentioned slurry composition for a non-aqueous secondary battery electrode, and a suitable abundance ratio of each component is the slurry composition. It is the same as the preferable abundance ratio of each component in. Further, the particulate polymer A and the particulate polymer B are present in the particle shape in the slurry composition, but may be in the particle shape in the electrode mixture layer formed by using the slurry composition. However, it may have any other shape.

Since the electrode for the non-aqueous secondary battery of the present invention uses the slurry composition containing the binder composition for the non-aqueous secondary battery electrode of the present invention, the electrode mixture layer and the current collector are good. To bind to. Therefore, the electrode for a non-aqueous secondary battery of the present invention has excellent peel strength. Further, since the electrode for a non-aqueous secondary battery of the present invention is formed by using a slurry composition containing the binder composition for a non-aqueous secondary battery electrode of the present invention, if the electrode is used, a cycle can be obtained. A secondary battery having excellent battery characteristics such as characteristics can be obtained. Further, when the binder composition containing the particulate polymer A2 is used, it is possible to make the non-aqueous secondary battery exhibit excellent rate characteristics.

<Method of manufacturing electrodes>
In the electrode for a non-aqueous secondary battery of the present invention, for example, the above-mentioned slurry composition is applied onto the current collector (coating step) and the slurry composition applied onto the current collector is dried. It is manufactured through a step of forming an electrode mixture layer on a current collector (drying step).

[Applying process]
The method for applying the slurry composition onto the current collector is not particularly limited, and a known method can be used. Specifically, as the coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method and the like can be used. At this time, the slurry composition may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after application and before drying can be appropriately set according to the thickness of the electrode mixture layer obtained by drying.

Here, as the current collector to which the slurry composition is applied, a material having electrical conductivity and which is electrochemically durable is used. Specifically, as the current collector, for example, a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum or the like can be used. In addition, one kind of the said material may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

[Drying process]
The method for drying the slurry composition on the current collector is not particularly limited, and a known method can be used, for example, a drying method using warm air, hot air, low humidity air, a vacuum drying method, infrared rays, an electron beam, or the like. A drying method by irradiation can be mentioned. By drying the slurry composition on the current collector in this way, an electrode mixture layer can be formed on the current collector, and an electrode for a secondary battery having the current collector and the electrode mixture layer can be obtained. it can.

After the drying step, the electrode mixture layer may be pressure-treated by using a die press or a roll press. By the pressurizing treatment, the adhesion between the electrode mixture layer and the current collector can be improved. When the electrode mixture layer contains a curable polymer, it is preferable to cure the polymer after the electrode mixture layer is formed.

(Non-aqueous secondary battery)
The non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, an electrolytic solution, and a separator, and uses the electrode for the non-aqueous secondary battery of the present invention as at least one of the positive electrode and the negative electrode. Since the non-aqueous secondary battery of the present invention includes the electrode for the non-aqueous secondary battery of the present invention, it is excellent in battery characteristics such as cycle characteristics. Further, when the binder composition containing the particulate polymer A2 is used, it is possible to make the non-aqueous secondary battery exhibit excellent rate characteristics.
The secondary battery of the present invention preferably uses the electrode for the secondary battery of the present invention as a negative electrode. Further, in the following, a case where the secondary battery is a lithium ion secondary battery will be described as an example, but the present invention is not limited to the following example.

<Electrode>
As described above, the electrode for a non-aqueous secondary battery of the present invention is used as at least one of a positive electrode and a negative electrode. That is, the positive electrode of the lithium ion secondary battery may be the electrode of the present invention and the negative electrode may be another known negative electrode, the negative electrode of the lithium ion secondary battery is the electrode of the present invention, and the positive electrode is another known positive electrode. And both the positive and negative electrodes of the lithium ion secondary battery may be the electrodes of the present invention.
As a known electrode other than the electrode for a non-aqueous secondary battery of the present invention, an electrode formed by forming an electrode mixture layer on a current collector using a known manufacturing method can be used.

<Electrolytic solution>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte of the lithium ion secondary battery, for example, a lithium salt is used. Examples of the lithium salt include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi. , (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi and the like. Among them, LiPF ₆ , LiClO ₄ , CF ₃ SO ₃ Li are preferable, and LiPF ₆ is particularly preferable because they are easily dissolved in a solvent and show a high degree of dissociation. One type of electrolyte may be used alone, or two or more types may be used in combination at any ratio. Normally, the more the supporting electrolyte with a higher dissociation degree is used, the higher the lithium ion conductivity tends to be. Therefore, the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.

The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte, and for example, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and the like. Carbonates such as butylene carbonate (BC) and ethyl methyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide. Kind; etc. are preferably used. Further, a mixed solution of these solvents may be used. Above all, it is preferable to use carbonates because the dielectric constant is high and the stable potential region is wide.
The concentration of the electrolyte in the electrolytic solution can be appropriately adjusted, for example, preferably 0.5 to 15% by mass, more preferably 2 to 13% by mass, and 5 to 10% by mass. Is more preferable. In addition, known additives such as vinylene carbonate, fluoroethylene carbonate, and ethyl methyl sulfone can be added to the electrolytic solution.

<Separator>
The separator is not particularly limited, and for example, the separator described in JP2012-204303 can be used. Among these, the film thickness of the entire separator can be reduced, and as a result, the ratio of the electrode active material in the secondary battery can be increased and the capacity per volume can be increased. A microporous membrane made of a resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferable.

<Manufacturing method of secondary battery>
In the secondary battery of the present invention, for example, a positive electrode and a negative electrode are overlapped with each other via a separator, and if necessary, the secondary battery is put into a battery container by winding or folding according to the battery shape, and electrolyzed into the battery container. It can be manufactured by injecting a liquid and sealing it. In order to prevent the internal pressure rise, overcharge / discharge, and the like inside the secondary battery, an overcurrent prevention element such as a fuse and a PTC element, an expanded metal, a lead plate, and the like may be provided, if necessary. The shape of the secondary battery may be, for example, a coin type, a button type, a sheet type, a cylindrical type, a square type, a flat type, or the like.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the following description, "%" and "part" representing quantities are based on mass unless otherwise specified.
Then, in Examples and Comparative Examples, the volume average particle diameter of various polymers, the swelling degree of the electrolytic solution of the particulate polymer, the tap density of the negative electrode active material, the stability of the slurry composition, the peel strength of the negative electrode, and the second. The cycle characteristics and rate characteristics of the next battery were measured and evaluated by the following methods.

<Volume average particle size>
Particle size distribution (volume basis) of the aqueous dispersion of the polymer adjusted to a solid content concentration of 0.1% by mass using a laser diffraction type particle size distribution measuring device (manufactured by Beckman Coulter, product name "LS-230"). Was measured. Then, in the obtained particle size distribution, the particle size at which the cumulative volume calculated from the small diameter side was 50% was determined and used as the volume average particle size (D50) of various polymers.
<Degree of swelling of electrolyte>
The prepared aqueous dispersion containing the particulate polymer was placed in a petri dish made of polytetrafluoroethylene and dried at 25 ° C. for 48 hours to prepare a polymer film as a test piece. The weight of this test piece was measured and set to W0. Next, this test piece was immersed in an electrolytic solution (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: LiPF _{6 having a} concentration of 1 M) at 60 ° C. for 72 hours. did. Then, the test piece was taken out from the electrolytic solution, the electrolytic solution on the surface of the test piece was wiped off, and the weight W1 of the test piece after immersion in the electrolytic solution was measured.
Using these weights W0 and W1, the electrolytic solution swelling degree S (times) was calculated with S = W1 / W0.
<Tap density>
The tap density of the negative electrode active material was measured using a powder tester (registered trademark) (manufactured by Hosokawa Micron, product name "PT-D"). Specifically, first, the powder of the negative electrode active material filled in the measuring container was ground on the upper surface of the container. Next, a cap attached to the measuring instrument was attached to the measuring container, powder of the negative electrode active material was additionally filled up to the upper edge of the attached cap, and the powder was repeatedly dropped from a height of 1.8 cm 180 times to perform tapping. After the tapping was completed, the cap was removed, and the powder of the negative electrode active material was ground again on the upper surface of the container. The sample that was worn after tapping was weighed, and the bulk density in this state was measured as the solidified bulk density, that is, the tap density (g / cm ³ ).
<Stability>
The prepared slurry composition M0 (g) was passed through an 80-mesh filtration filter, and the time t (seconds) required to filter to the remaining amount M1 (g) (<M0) was measured. The filtration rate V (g / sec) is calculated by the following formula:
V = (M0-M1) / t
Was calculated using, and evaluated according to the following criteria. The larger the value of the filtration rate V, the less the agglomerates in the slurry composition, that is, the higher the stability of the slurry composition.
A: Filtration rate V is 0.8 g / sec or more B: Filtration rate V is 0.5 g / sec or more and less than 0.8 g / sec C: Filtration rate V is 0.3 g / sec or more and less than 0.5 g / sec D: Filtration rate V is less than 0.3 g / sec <Peel strength>
The prepared negative electrode was cut into a rectangle having a length of 100 mm and a width of 10 mm to obtain a test piece. A cellophane tape was attached to the surface of the negative electrode mixture layer with the surface of the negative electrode mixture layer facing down. At this time, as the cellophane tape, the one specified in JIS Z1522 was used. The cellophane tape was fixed to the test table. Then, the stress when one end of the current collector was pulled vertically upward at a tensile speed of 50 mm / min and peeled off was measured. This measurement was performed three times, the average value was obtained, and the average value was taken as the peel strength. The larger the peel strength, the greater the binding force of the negative electrode mixture layer to the current collector, that is, the greater the adhesion strength.
A: Peel strength is 24 N / m or more B: Peel strength is 19 N / m or more and less than 24 N / m C: Peel strength is 14 N / m or more and less than 19 N / m D: Peel strength is less than 14 N / m <Cycle characteristics>
The prepared lithium ion secondary battery having a capacity of 800 mAh was allowed to stand for 24 hours in an environment of 25 ° C. Then, in an environment of 25 ° C., a charge / discharge operation was performed in which the battery was charged to 4.35 V at a charge rate of 1 C and discharged to 3.0 V at a discharge rate of 1 C, and the initial capacity C0 was measured. Further, the same charge / discharge operation was repeated in an environment of 45 ° C., and the capacity C1 after 300 cycles was measured. Then, the capacity retention rate ΔC = (C1 / C0) × 100 (%) was calculated and evaluated according to the following criteria. The higher the value of the capacity retention rate, the less the decrease in the discharge capacity and the better the cycle characteristics.
A: Capacity retention rate ΔC is 80% or more B: Capacity retention rate ΔC is 75% or more and less than 80% C: Capacity retention rate ΔC is 70% or more and less than 75% D: Capacity retention rate ΔC is less than 70% <Rate characteristics>
The prepared lithium ion secondary battery having a capacity of 800 mAh was allowed to stand for 24 hours in an environment of 25 ° C. Then, after measuring the initial capacity C0'by the same method as the above-mentioned "cycle characteristics", the lithium ion secondary battery is subjected to a constant current constant voltage method (cutoff condition) up to 4.35 V at 0.2 C in an environment of 25 ° C. : 0.02C) was fully charged. Then, under a −10 ° C. environment, a constant current was discharged at 0.2 C to 3.0 V, and the discharge capacity C1 ′ at that time was measured. Then, the lithium ion secondary battery is fully charged again by the constant current constant voltage method (cutoff condition: 0.02C) of 4.35V under a 25 ° C environment, and then 3.0V at 1C under a −10 ° C environment. The constant current was discharged up to, and the discharge capacity C2'at that time was measured. Then, the capacity retention rate ΔC ′ = (C2 ′ / C1 ′) × 100 (%) was calculated and evaluated according to the following criteria. The higher the value of the capacity retention rate, the better the rate characteristics (low temperature characteristics).
A: Capacity retention rate ΔC'is 55% or more B: Capacity retention rate ΔC'is less than 50% 55% or more C: Capacity retention rate ΔC'is less than 45% 50% or more D: Capacity retention rate ΔC'is less than 45%

− Experiment 1-
(Example 1-1)
<Preparation of Particulate Polymer A1>
5 parts of acrylic acid as a carboxylic acid group-containing monomer and 2.5 parts of sodium lauryl sulfate as an emulsifier (used after diluting to 20% with ion-exchanged water) were added to container X, stirred, and emulsified. After that, a natural rubber latex (manufactured by Musashino Chemical Co., Ltd., product name "LA type", solid content concentration 62%, natural in latex) containing natural rubber (NR) particles having a volume average particle diameter of 0.88 μm in container X. The polymer constituting the rubber particles contained 95% or more of isoprene units) was added in an amount equivalent to 95 parts of solid content and left to stand for 2 hours, and then stirred. After sufficient stirring, 0.6 parts of tetraethylenepentaamine and 0.6 parts of t-butylhydrooxide as a polymerization initiator were further added to the container X to initiate graft polymerization. The reaction temperature was maintained at 30 ° C. After 1.5 hours from the start of graft polymerization, the temperature was raised to 70 ° C., and after holding for another 3 hours, it was confirmed that the polymerization addition rate was 97% or more, and the reaction was stopped to obtain a polymer for the trunk portion. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A1 in which a graft portion consisting of only a carboxylic acid group-containing monomer unit was introduced into the particles of natural rubber was obtained. The volume average particle size of the obtained particulate polymer A1 was measured, and the volume average particle size ratio Δd was calculated. The results are shown in Table 1.
<Preparation of Particulate Polymer B>
33 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 62 parts of styrene as an aromatic vinyl monomer, 4 parts of itaconic acid as a carboxylic acid group-containing monomer, and 0 sodium lauryl sulfate as an emulsifier. . 3 parts, pressure resistance of 1 part of potassium persulfate as a polymerization initiator at the same time as starting the addition of the mixture from the container Y containing the mixture of 0.3 parts of tert-dodecyl mercaptan as a chain transfer agent to the pressure resistant container Z Addition to the container Z was started, and polymerization was started. The reaction temperature was maintained at 75 ° C.
In addition, 4 hours after the start of polymerization (after adding 70% of the mixture to the pressure resistant vessel Z), 1 part of 2-hydroxyethyl acrylate (-2-hydroxyethyl acrylate) as a hydroxyl group-containing monomer was added. It was added to the pressure resistant container Z for 30 minutes.
After 5 hours and 30 minutes from the start of the polymerization, the addition of the entire amount of the above-mentioned monomer was completed. Then, it was further heated to 85 ° C. and reacted for 6 hours.
When the polymerization conversion rate reached 97%, the mixture was cooled and the reaction was stopped to obtain a mixture containing a particulate polymer. A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate polymer to adjust the pH to 8. Then, the unreacted monomer was removed by hot vacuum distillation. Then, it was cooled to obtain an aqueous dispersion (solid content concentration: 40%) containing the particulate polymer B having a volume average particle diameter of 0.15 μm.
<Preparation of binder composition>
The aqueous dispersion of the particulate polymer A1 and the aqueous dispersion of the particulate polymer B are mixed with the particulate polymer A1 and the particulate polymer B in a solid content ratio, and the particulate polymer A1: particulate weight. It was put into a container so that coalescence B = 70: 30. Then, the mixture was stirred with a three-one motor for 1 hour to obtain a binder composition for a non-aqueous secondary battery electrode.
<Preparation of slurry composition>
70 parts of artificial graphite (manufactured by Hitachi Chemical Co., Ltd., product name "MAG-E") and 25.6 parts of natural graphite (manufactured by Nippon Carbon Co., Ltd., product name "604A") as a negative electrode active material in a planetary mixer with a disper. , 1 part of carbon black (manufactured by TIMCAL, product name "Super C65") as a conductive material, and 2% aqueous solution of carboxymethyl cellulose (manufactured by Nippon Paper Chemicals Co., Ltd., product name "MAC-350HC") as a viscosity modifier are solid. A mixture was obtained by adding 1.2 parts equivalent to minutes. The obtained mixture was adjusted to a solid content concentration of 60% with ion-exchanged water, and then mixed at 25 ° C. for 60 minutes. Next, after adjusting the solid content concentration to 52% with ion-exchanged water, the mixture was further mixed at 25 ° C. for 15 minutes to obtain a mixed solution. To the obtained mixed solution, 2.2 parts of the binder composition for a non-aqueous secondary battery electrode equivalent to solid content and ion-exchanged water were added, and the final solid content concentration was adjusted to 48%. After further mixing for 10 minutes, defoaming treatment was performed under reduced pressure to obtain a slurry composition for a negative electrode of a non-aqueous secondary battery having good fluidity.
The stability of the obtained slurry composition was evaluated. The results are shown in Table 1. The tap density of the negative electrode active material (a mixture obtained by mixing the above-mentioned artificial graphite and natural graphite at the above-mentioned ratio) was separately measured. The results are shown in Table 1.
<Manufacturing of negative electrode>
The obtained slurry composition for the negative electrode of a non-aqueous secondary battery is applied to a copper foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying is about 150 μm, and dried. I let you. This drying was carried out by transporting the copper foil at a rate of 0.5 m / min in an oven at 60 ° C. for 2 minutes. Then, it was heat-treated at 120 degreeC for 2 minutes, and the negative electrode raw fabric before pressing was obtained. The negative electrode raw material before pressing was rolled by a roll press to obtain a negative electrode after pressing with a thickness of the negative electrode mixture layer of 80 μm.
Then, the peel strength of the negative electrode was evaluated. The results are shown in Table 1.
<Preparation of positive electrode>
100 parts of LiCoO ₂ having a volume average particle diameter of 12 μm as a positive electrode active material, ₂ parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., product name “HS-100”) as a conductive material, and polyfluoridene fluoride as a binder. Two parts of vinylidene fluoride (manufactured by Kureha, product name "# 7208") equivalent to solid content and N-methylpyrrolidone as a solvent were mixed to adjust the total solid content concentration to 70%. These were mixed by a planetary mixer to obtain a slurry composition for a positive electrode of a non-aqueous secondary battery.
The obtained slurry composition for the positive electrode of a non-aqueous secondary battery is applied on an aluminum foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying is about 150 μm, and dried. I let you. This drying was carried out by transporting the aluminum foil at a speed of 0.5 m / min in an oven at 60 ° C. for 2 minutes. Then, it was heat-treated at 120 degreeC for 2 minutes, and the positive electrode raw fabric was obtained.
Then, the obtained positive electrode raw fabric was rolled using a roll press machine to obtain a positive electrode provided with a positive electrode mixture layer.
<Preparation of separator>
A single-layer polypropylene separator (manufactured by Cellguard, product name "Cellguard 2500") was cut out to a size of 120 cm x 5.5 cm.
<Making secondary batteries>
The obtained positive electrode after pressing was cut out into a rectangle of 49 cm × 5 cm and placed so that the surface on the positive electrode mixture layer side was on the upper side, and a separator cut out to 120 cm × 5.5 cm was placed on the positive electrode mixture layer. Was arranged so as to be located on the left side in the longitudinal direction of the separator. Further, the obtained negative electrode after pressing is cut into a rectangle of 50 cm × 5.2 cm, and the negative electrode is located on the separator so that the surface on the negative electrode mixture layer side faces the separator and the negative electrode is located on the right side in the longitudinal direction of the separator. Arranged as. Then, the obtained laminated body was wound by a winding machine to obtain a wound body. This wound body is wrapped with an aluminum packaging material exterior as the battery exterior, and the electrolyte (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: concentration 1M). LiPF ₆ ) was injected so that no air remained, and the opening of the exterior of the aluminum packaging material was closed with a heat seal at 150 ° C. to manufacture a wound lithium ion secondary battery having a capacity of 800 mAh.
Then, the cycle characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 1.

(Example 1-2)
The binder composition, slurry composition, negative electrode, positive electrode, separator and secondary battery were prepared in the same manner as in Example 1-1 except that the graft copolymer prepared as described below was used as the particulate polymer A1. Manufactured. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.
<Preparation of Particulate Polymer A1>
Isoprene rubber (manufactured by Nippon Zeon Corporation, product name "Nipol IR2200") was dissolved in toluene to prepare an isoprene rubber solution having a concentration of 25%.
Subsequently, a mixture of sodium linear alkylbenzene sulfonate, sodium alkylpolyoxyethylene sulfonate, and sodium alkylpolyoxyethylene sulfosuccinate at a ratio of 1: 1: 1 was dissolved in ion-exchanged water to have a total solid content concentration of 2. % Aqueous solution was prepared.
500 g of the isoprene rubber solution and 500 g of the aqueous solution were put into a tank, and the mixture was stirred to perform premixing. Subsequently, the obtained premixed solution is transferred from the tank to a milder (manufactured by Pacific Kiko Co., Ltd., product name "MDN303V") at a speed of 100 g / min by a metering pump, stirred at a rotation speed of 20000 rpm, and emulsified. (Phase inversion emulsification).
Next, toluene in the obtained emulsion was distilled off under reduced pressure with a rotary evaporator, and then the mixture was left to stand and separated in a chromatographic column with a cock for 1 day, and the lower layer portion after separation was removed to concentrate the mixture. It was.
Then, the upper layer portion was filtered through a 100-mesh wire mesh to prepare a latex containing polyisoprene (IR) particles. The solid content concentration of the obtained polyisoprene latex was 60%, and the volume average particle size was 1.1 μm.
The same operation as in Example 1-1 was carried out except that the obtained polyisoprene latex was used instead of the natural rubber latex and methacrylic acid was used instead of the acrylic acid, and the polymer of the trunk portion was used. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A1 in which a graft portion consisting of only a carboxylic acid group-containing monomer unit was introduced into the particles of polyisoprene was obtained.

(Example 1-3)
The binder composition, slurry composition, negative electrode, positive electrode, separator and secondary battery were prepared in the same manner as in Example 1-1 except that the graft copolymer prepared as described below was used as the particulate polymer A1. Manufactured. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.
<Preparation of Particulate Polymer A1>
A butadiene rubber (manufactured by Nippon Zeon Corporation, product name "Nipol BR1220") was dissolved in toluene to prepare a butadiene rubber solution having a concentration of 25%.
Subsequently, a mixture of sodium linear alkylbenzene sulfonate, sodium alkylpolyoxyethylene sulfonate, and sodium alkylpolyoxyethylene sulfosuccinate at a ratio of 1: 1: 1 was dissolved in ion-exchanged water to have a total solid content concentration of 2. % Aqueous solution was prepared.
500 g of the butadiene rubber solution and 500 g of the aqueous solution were put into a tank and stirred to perform premixing. Subsequently, the obtained premixed solution is transferred from the tank to a milder (manufactured by Pacific Kiko Co., Ltd., product name "MDN303V") at a speed of 100 g / min by a metering pump, stirred at a rotation speed of 20000 rpm, and emulsified. (Phase inversion emulsification).
Next, toluene in the obtained emulsion was distilled off under reduced pressure with a rotary evaporator, and then the mixture was left to stand and separated in a chromatographic column with a cock for 1 day, and the lower layer portion after separation was removed to concentrate the mixture. It was.
Then, the upper layer portion was filtered through a 100-mesh wire mesh to prepare a latex containing polybutadiene (BR) particles. The solid content concentration of the obtained polybutadiene latex was 60%, and the volume average particle size was 1.03 μm.
The same operation as in Example 1-1 was carried out except that the obtained polybutadiene latex was used in place of the natural rubber latex, and a single amount of carboxylic acid group was contained in the polybutadiene particles as the polymer of the trunk portion. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A1 into which a graft portion consisting of only a body unit was introduced was obtained.

(Example 1-4)
In the preparation of the particulate polymer A1, 26 parts of methacrylic acid was used instead of acrylic acid, and the amount of natural rubber latex was 74 parts equivalent to the solid content, but the binder was the same as in Example 1-1. A composition, a slurry composition, a negative electrode, a positive electrode, a separator and a secondary battery were manufactured. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.

(Example 1-5)
Similar to Example 1-1, except that 1.5 parts of methacrylic acid was used instead of acrylic acid and the amount of natural rubber latex was 98.5 parts equivalent to the solid content in the preparation of the particulate polymer A1. A binder composition, a slurry composition, a negative electrode, a positive electrode, a separator, and a secondary battery were manufactured. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.

(Example 1-6)
The binder composition, slurry composition, negative electrode, positive electrode, separator and secondary battery were prepared in the same manner as in Example 1-1 except that the graft copolymer prepared as described below was used as the particulate polymer A1. Manufactured. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.
<Preparation of Particulate Polymer A1>
Dilute natural rubber latex (manufactured by Musashino Chemical Co., Ltd., product name "LA type", the polymer constituting the natural rubber particles in the latex contains 95% or more of isoprene units)) until the solid content concentration reaches 10%. , Was allowed to stand for 30 days. Then, 15% of the total amount of supernatant was removed to obtain a latex containing natural rubber (NR) particles having a volume average particle diameter of 2.18 μm.
The same operation as in Example 1-1 was carried out except that 80 parts of the obtained natural rubber latex was used in terms of solid content and 20 parts of methacrylic acid was used instead of acrylic acid, and the polymer of the trunk part was used. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A1 in which a graft portion consisting of only a carboxylic acid group-containing monomer unit was introduced into the particles of natural rubber was obtained.

(Example 1-7)
The binder composition, slurry composition, negative electrode, positive electrode, and separator are the same as in Example 1-1 except that only the particulate polymer A1 is used without using the particulate polymer B when preparing the binder composition. And manufactured secondary batteries. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.

(Comparative Example 1-1)
In the preparation of the particulate polymer A1, 35 parts of methacrylic acid was used instead of acrylic acid, and the amount of natural rubber latex was 65 parts equivalent to the solid content, but the binder was the same as in Example 1-7. A composition, a slurry composition, a negative electrode, a positive electrode, a separator and a secondary battery were manufactured. Then, various evaluations were performed in the same manner as in Example 1-1. The results are shown in Table 1.

In Table 1 shown below,
"NR" indicates natural rubber,
"IR" indicates polyisoprene,
"BR" indicates polybutadiene,
"IP" indicates the isoprene unit,
"BD" represents 1,3-butadiene units,
"AA" indicates an acrylic acid unit,
"MAA" indicates a methacrylic acid unit,
"ST" indicates a styrene unit,
"IA" indicates an itaconic acid unit,
"2-HEA" represents a 2-hydroxyethyl acrylate unit,
"CB" indicates carbon black.

From Table 1, the particulate polymer A1 containing an aliphatic conjugated diene monomer unit in an amount of 70% by mass or more and 99% by mass or less and a carboxylic acid group-containing monomer unit in an amount of 1% by mass or more and 30% by mass or less. It can be seen that in Examples 1-1 to 1-7 using the above, a slurry composition having excellent stability, a negative electrode having excellent peel strength, and a secondary battery having excellent cycle characteristics can be obtained. Further, from Table 1, comparison using the particulate polymer A1 in which the content ratio of the aliphatic conjugated diene monomer unit is less than 70% by mass and the content ratio of the carboxylic acid group-containing monomer unit is more than 30% by mass is compared. In Example 1-1, it can be seen that the peel strength of the negative electrode and the cycle characteristics of the secondary battery are lowered.

-Experiment 2-
(Example 2-1)
<Preparation of particulate polymer A2>
Add 20 parts of methyl methacrylate as a (meth) acrylic acid ester monomer and 2.5 parts of sodium lauryl sulfate as an emulsifier (diluted to 20% with ion-exchanged water) to container X, stir and emulsify. It was. After that, a natural rubber latex (manufactured by Musashino Chemical Co., Ltd., product name "LA type", solid content concentration 62%, natural in latex) containing natural rubber (NR) particles having a volume average particle diameter of 0.88 μm in container X. The polymer constituting the rubber particles contained 95% or more of isoprene units) was added in an amount equivalent to 80 parts of solid content and left to stand for 2 hours, and then stirred. After sufficient stirring, 0.6 parts of tetraethylenepentaamine and 0.6 parts of t-butylhydrooxide as a polymerization initiator were further added to the container X to initiate graft polymerization. The reaction temperature was maintained at 28 ° C. Nine hours after the start of graft polymerization, it was confirmed that the polymerization addition rate was 97% or more, the reaction was stopped, and the (meth) acrylic acid ester monomer was used with respect to the particles of natural rubber as the polymer of the trunk portion. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A2 into which a graft portion consisting of only units was introduced was obtained. The volume average particle size and the degree of swelling of the electrolytic solution of the obtained particulate polymer A2 were measured, and the volume average particle size ratio Δd was calculated. The results are shown in Table 2.
<Preparation of Particulate Polymer B>
In the same manner as in Example 1-1, an aqueous dispersion (solid content concentration: 40%) containing the particulate polymer B having a volume average particle diameter of 0.15 μm was obtained.
<Preparation of binder composition>
The aqueous dispersion of the particulate polymer A2 and the aqueous dispersion of the particulate polymer B are mixed with the particulate polymer A2 and the particulate polymer B in a solid content ratio, and the particulate polymer A2: particulate weight. It was put into a container so that coalescence B = 60: 40. Then, the mixture was stirred with a three-one motor for 1 hour to obtain a binder composition for a non-aqueous secondary battery electrode.
<Preparation of slurry composition>
70 parts of artificial graphite (manufactured by Hitachi Chemical Co., Ltd., product name "MAG-E") and 25.6 parts of natural graphite (manufactured by Nippon Carbon Co., Ltd., product name "604A") as a negative electrode active material in a planetary mixer with a disper. , 1 part of carbon black (manufactured by TIMCAL, product name "Super C65") as a conductive material, and 2% aqueous solution of carboxymethyl cellulose (manufactured by Nippon Paper Chemicals Co., Ltd., product name "MAC-350HC") as a viscosity modifier are solid. A mixture was obtained by adding 1.2 parts equivalent to minutes. The obtained mixture was adjusted to a solid content concentration of 60% with ion-exchanged water, and then mixed at 25 ° C. for 60 minutes. Next, after adjusting the solid content concentration to 52% with ion-exchanged water, the mixture was further mixed at 25 ° C. for 15 minutes to obtain a mixed solution. To the obtained mixed solution, 2.2 parts of the binder composition for a non-aqueous secondary battery electrode equivalent to solid content and ion-exchanged water were added, and the final solid content concentration was adjusted to 48%. After further mixing for 10 minutes, defoaming treatment was performed under reduced pressure to obtain a slurry composition for a negative electrode of a non-aqueous secondary battery having good fluidity.
The stability of the obtained slurry composition was evaluated. The results are shown in Table 2. The tap density of the negative electrode active material (a mixture obtained by mixing the above-mentioned artificial graphite and natural graphite at the above-mentioned ratio) was separately measured. The results are shown in Table 2.
<Manufacturing of negative electrode>
The obtained slurry composition for the negative electrode of a non-aqueous secondary battery is applied to a copper foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying is about 150 μm, and dried. I let you. This drying was carried out by transporting the copper foil at a rate of 0.5 m / min in an oven at 60 ° C. for 2 minutes. Then, it was heat-treated at 120 degreeC for 2 minutes, and the negative electrode raw fabric before pressing was obtained. The negative electrode raw material before pressing was rolled by a roll press to obtain a negative electrode after pressing with a thickness of the negative electrode mixture layer of 80 μm.
Then, the peel strength of the negative electrode was evaluated. The results are shown in Table 2.
<Preparation of positive electrode>
A positive electrode provided with a positive electrode mixture layer was obtained in the same manner as in Example 1-1.
<Preparation of separator>
A single-layer polypropylene separator (manufactured by Cellguard, product name "Cellguard 2500") was cut out to a size of 120 cm x 5.5 cm.
<Making secondary batteries>
The obtained positive electrode after pressing was cut out into a rectangle of 49 cm × 5 cm and placed so that the surface on the positive electrode mixture layer side was on the upper side, and a separator cut out to 120 cm × 5.5 cm was placed on the positive electrode mixture layer. Was arranged so as to be located on the left side in the longitudinal direction of the separator. Further, the obtained negative electrode after pressing is cut into a rectangle of 50 cm × 5.2 cm, and the negative electrode is located on the separator so that the surface on the negative electrode mixture layer side faces the separator and the negative electrode is located on the right side in the longitudinal direction of the separator. Arranged as. Then, the obtained laminated body was wound by a winding machine to obtain a wound body. This wound body is wrapped with an aluminum packaging material exterior as the battery exterior, and the electrolyte (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: concentration 1M). LiPF ₆ ) was injected so that no air remained, and the opening of the exterior of the aluminum packaging material was closed with a heat seal at 150 ° C. to manufacture a wound lithium ion secondary battery having a capacity of 800 mAh.
Then, the cycle characteristics and rate characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

(Example 2-2)
The binder composition, slurry composition, negative electrode, positive electrode, separator and secondary battery were prepared in the same manner as in Example 2-1 except that the graft copolymer prepared as follows was used as the particulate polymer A2. Manufactured. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.
<Preparation of particulate polymer A2>
Isoprene rubber (manufactured by Nippon Zeon Corporation, product name "Nipol IR2200") was dissolved in toluene to prepare an isoprene rubber solution having a concentration of 25%.
Subsequently, a mixture of sodium linear alkylbenzene sulfonate, sodium alkylpolyoxyethylene sulfonate, and sodium alkylpolyoxyethylene sulfosuccinate at a ratio of 1: 1: 1 was dissolved in ion-exchanged water to have a total solid content concentration of 2. % Aqueous solution was prepared.
500 g of the isoprene rubber solution and 500 g of the aqueous solution were put into a tank, and the mixture was stirred to perform premixing. Subsequently, the obtained premixed solution is transferred from the tank to a milder (manufactured by Pacific Kiko Co., Ltd., product name "MDN303V") at a speed of 100 g / min by a metering pump, stirred at a rotation speed of 20000 rpm, and emulsified. (Phase inversion emulsification).
Next, toluene in the obtained emulsion was distilled off under reduced pressure with a rotary evaporator, and then the mixture was left to stand and separated in a chromatographic column with a cock for 1 day, and the lower layer portion after separation was removed to concentrate the mixture. It was.
Then, the upper layer portion was filtered through a 100-mesh wire mesh to prepare a latex containing polyisoprene (IR) particles. The solid content concentration of the obtained polyisoprene latex was 60%, and the volume average particle size was 1.1 μm.
The same operation as in Example 2-1 was carried out except that the obtained polyisoprene latex was used in place of the natural rubber latex, and (meth) acrylic was applied to the polyisoprene particles as the polymer of the trunk portion. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A2 into which a graft portion consisting of only an acid ester monomer unit was introduced was obtained.

(Example 2-3)
The binder composition, slurry composition, negative electrode, positive electrode, separator and secondary battery were prepared in the same manner as in Example 2-1 except that the graft copolymer prepared as follows was used as the particulate polymer A2. Manufactured. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2-1.
<Preparation of particulate polymer A2>
A butadiene rubber (manufactured by Nippon Zeon Corporation, product name "Nipol BR1220") was dissolved in toluene to prepare a butadiene rubber solution having a concentration of 25%.
Subsequently, a mixture of sodium linear alkylbenzene sulfonate, sodium alkylpolyoxyethylene sulfonate, and sodium alkylpolyoxyethylene sulfosuccinate at a ratio of 1: 1: 1 was dissolved in ion-exchanged water to have a total solid content concentration of 2. % Aqueous solution was prepared.
500 g of the butadiene rubber solution and 500 g of the aqueous solution were put into a tank and stirred to perform premixing. Subsequently, the obtained premixed solution is transferred from the tank to a milder (manufactured by Pacific Kiko Co., Ltd., product name "MDN303V") at a speed of 100 g / min by a metering pump, stirred at a rotation speed of 20000 rpm, and emulsified. (Phase inversion emulsification).
Next, toluene in the obtained emulsion was distilled off under reduced pressure with a rotary evaporator, and then the mixture was left to stand and separated in a chromatographic column with a cock for 1 day, and the lower layer portion after separation was removed to concentrate the mixture. It was.
Then, the upper layer portion was filtered through a 100-mesh wire mesh to prepare a latex containing polybutadiene (BR) particles. The solid content concentration of the obtained polybutadiene latex was 60%, and the volume average particle size was 1.02 μm.
The same operation as in Example 2-1 was carried out except that the obtained polybutadiene latex was used in place of the natural rubber latex, and the (meth) acrylic acid ester was applied to the polybutadiene particles as the polymer of the trunk portion. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A2 into which a graft portion composed of only monomer units was introduced was obtained.

(Example 2-4)
In the preparation of the particulate polymer A2, the binder composition and the slurry composition were the same as in Example 2-1 except that the amount of methyl methacrylate was 26 parts and the amount of natural rubber latex was 74 parts equivalent to the solid content. Manufactured products, negative electrodes, positive electrodes, separators and secondary batteries. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.

(Example 2-5)
In the preparation of the particulate polymer A2, the binder composition and the slurry composition were the same as in Example 2-1 except that the amount of methyl methacrylate was 8 parts and the amount of natural rubber latex was 92 parts equivalent to the solid content. Manufactured products, negative electrodes, positive electrodes, separators and secondary batteries. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.

(Example 2-6)
The binder composition, slurry composition, negative electrode, positive electrode, separator and secondary battery were prepared in the same manner as in Example 2-1 except that the graft copolymer prepared as follows was used as the particulate polymer A2. Manufactured. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.
<Preparation of particulate polymer A2>
Dilute natural rubber latex (manufactured by Musashino Chemical Co., Ltd., product name "LA type", the polymer constituting the natural rubber particles in the latex contains 95% or more of isoprene units) until the solid content concentration reaches 10%. It was allowed to stand for 30 days. Then, 15% of the total amount of supernatant was removed to obtain a latex containing natural rubber (NR) particles having a volume average particle diameter of 2.15 μm.
The same operation as in Example 2-1 was performed except that the obtained natural rubber latex was used, and only the (meth) acrylic acid ester monomer unit was applied to the natural rubber particles as the polymer of the trunk portion. An aqueous dispersion (solid content concentration: 40%) containing the particulate polymer A2 into which the graft portion was introduced was obtained.

(Example 2-7)
The binder composition, slurry composition, negative electrode, positive electrode, separator in the same manner as in Example 2-1 except that only the particulate polymer A2 was used without using the particulate polymer B when preparing the binder composition. And manufactured secondary batteries. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.

(Comparative Example 2-1)
In the preparation of the particulate polymer A2, the binder composition and the slurry composition were the same as in Example 2-7, except that the amount of methyl methacrylate was 35 parts and the amount of natural rubber latex was 65 parts equivalent to the solid content. Manufactured products, negative electrodes, positive electrodes, separators and secondary batteries. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.

(Comparative Example 2-2)
Natural rubber latex (manufactured by Musashino Chemical Co., Ltd., product name) containing natural rubber (NR) particles having a volume average particle diameter of 0.88 μm without a graft portion introduced in place of the aqueous dispersion of the particulate polymer A2. The binder composition is the same as in Example 2-7 except that "LA type", the solid content concentration is 62%, and the polymer constituting the natural rubber particles in the latex contains 95% or more of isoprene units). , Slurry composition, negative electrode, positive electrode, separator and secondary battery were manufactured. Then, various evaluations were performed in the same manner as in Example 2-1. The results are shown in Table 2.

In Table 2 shown below,
"NR" indicates natural rubber,
"IR" indicates polyisoprene,
"BR" indicates polybutadiene,
"IP" indicates the isoprene unit,
"BD" represents 1,3-butadiene units,
"MMA" represents a methyl methacrylate unit,
"ST" indicates a styrene unit,
"IA" indicates an itaconic acid unit,
"2-HEA" represents a 2-hydroxyethyl acrylate unit,
"CB" indicates carbon black.

From Table 2, the aliphatic conjugated diene monomer unit is contained in an amount of 70% by mass or more and 95% by mass or less, and the (meth) acrylic acid ester monomer unit is contained in a ratio of 1% by mass or more and 30% by mass or less. In Examples 2-1 to 2-7 using the particulate polymer A2 having an electrolytic solution swelling degree of 1.2 times or more and 7.0 times or less, a slurry composition having excellent stability, a negative electrode having excellent peel strength, and a negative electrode It can be seen that a secondary battery having excellent cycle characteristics and rate characteristics can be obtained. Further, from Table 2, the content ratio of the aliphatic conjugated diene monomer unit is less than 70% by mass, the content ratio of the (meth) acrylic acid ester monomer unit is more than 30% by mass, and the degree of swelling of the electrolytic solution is high. In Comparative Example 2-1 using the particulate polymer A2 having a mass of more than 7.0 times, it can be seen that the cycle characteristics and rate characteristics of the secondary battery are deteriorated. Further, in Comparative Example 2-2 using the particulate polymer A2 in which the content ratio of the (meth) acrylic acid ester monomer unit was less than 1% by mass, the stability of the slurry composition and the rate characteristics of the secondary battery were obtained. It can be seen that is reduced.

According to the present invention, a binder composition for a non-aqueous secondary battery electrode capable of forming an electrode for a non-aqueous secondary battery which is excellent in peel strength and can exhibit excellent cycle characteristics in a non-aqueous secondary battery. And a slurry composition for a non-aqueous secondary battery electrode can be provided.
Further, according to the present invention, it is possible to provide an electrode for a non-aqueous secondary battery which has excellent peel strength and can exhibit excellent cycle characteristics in a non-aqueous secondary battery.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery having excellent battery characteristics such as cycle characteristics.

Claims (15)

A binder composition for a non-aqueous secondary battery electrode containing a particulate polymer A1.
The particulate polymer A1 contains an aliphatic conjugated diene monomer unit in an amount of 70% by mass or more and 99% by mass or less, and a carboxylic acid group-containing monomer unit in a proportion of 1% by mass or more and 30% by mass or less. Binder composition for aqueous secondary battery electrodes. A binder composition for a non-aqueous secondary battery electrode containing a particulate polymer A2.
The particulate polymer A2 contains an aliphatic conjugated diene monomer unit in an amount of 70% by mass or more and 95% by mass or less, and a (meth) acrylic acid ester monomer unit in a proportion of 1% by mass or more and 30% by mass or less. ,
A binder composition for a non-aqueous secondary battery electrode, wherein the electrolytic solution swelling degree of the particulate polymer A2 is 1.2 times or more and 7.0 times or less. The binder composition for a non-aqueous secondary battery electrode according to claim 1, wherein the particulate polymer A1 is a graft copolymer. The binder composition for a non-aqueous secondary battery electrode according to claim 1 or 3, wherein the volume average particle diameter of the particulate polymer A1 is 0.6 μm or more and 2.5 μm or less. Further containing particulate polymer B
The binder composition for a non-aqueous secondary battery electrode according to claim 4, wherein the volume average particle diameter of the particulate polymer B is 0.01 μm or more and less than 0.6 μm. The non-aqueous compound according to claim 5, wherein the content of the particulate polymer A1 is 50% by mass or more and 90% by mass or less of the total content of the particulate polymer A1 and the particulate polymer B. Binder composition for next battery electrode. The binder composition for a non-aqueous secondary battery electrode according to claim 2, wherein the particulate polymer A2 is a graft copolymer. The binder composition for a non-aqueous secondary battery electrode according to claim 2 or 7, wherein the volume average particle diameter of the particulate polymer A2 is 0.6 μm or more and 2.5 μm or less. Further containing particulate polymer B
The binder composition for a non-aqueous secondary battery electrode according to claim 8, wherein the volume average particle diameter of the particulate polymer B is 0.01 μm or more and less than 0.6 μm. The non-aqueous compound according to claim 9, wherein the content of the particulate polymer A2 is 50% by mass or more and 90% by mass or less of the total content of the particulate polymer A2 and the particulate polymer B. Binder composition for next battery electrode. A slurry composition for a non-aqueous secondary battery electrode, which comprises an electrode active material and a binder composition for a non-aqueous secondary battery electrode according to any one of claims 1 to 10. The slurry composition for a non-aqueous secondary battery electrode according to claim 11, wherein the tap density of the electrode active material is 1.1 g / cm ³ or less. The slurry composition for a non-aqueous secondary battery electrode according to claim 11 or 12, further comprising a conductive material. An electrode for a non-aqueous secondary battery, comprising an electrode mixture layer formed by using the slurry composition for a non-aqueous secondary battery electrode according to any one of claims 11 to 13. Equipped with positive and negative electrodes, electrolyte and separator,
A non-aqueous secondary battery in which at least one of the positive electrode and the negative electrode is the electrode for the non-aqueous secondary battery according to claim 14.